add persisted set ordering

backend/database/migrations/2026_07_31_000000_add_sort_order_to_sets_table.php

@@ -0,0 +1,38 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('sets', function (Blueprint $table): void {
+            $table->unsignedInteger('sort_order')->nullable();
+        });
+
+        $setIds = DB::table('sets')->orderBy('id')->pluck('id');
+        $sortOrder = 1;
+        foreach ($setIds as $setId) {
+            DB::table('sets')
+                ->where('id', $setId)
+                ->update(['sort_order' => $sortOrder]);
+            $sortOrder++;
+        }
+
+        Schema::table('sets', function (Blueprint $table): void {
+            $table->unsignedInteger('sort_order')
+                ->nullable(false)
+                ->change();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('sets', function (Blueprint $table): void {
+            $table->dropColumn('sort_order');
+        });
+    }
+};